1. Field of the Invention
The present invention relates to a roller for an installation for the continuous electrolytic processing of metallic or metallised materials in strips.
2. Description of the Prior Art
In known installations for continuous electrolytic processing, the electric current necessary for the electrolytic process is transmitted continuously to the metallic strip in the course of treatment through rollers placed above the processing tanks. The intensity of the electric current passing through the roller is very high and can reach, according to the case, 10,000 to 20,000 amperes. It is therefore necessary to have very solid rollers, which are good conductors of electricity and of heat and which have good resistance to wear and to corrosion. In addition, the heating produced in the course of the processing necessitates effective cooling by means of the circulation of water inside the rollers: the latter are therefore hollow.
Among rollers designed for this type of processing at the present time, the most customary type comprises a shaft on which two flanges, supporting an outer collar, are shrunk on. These elements are of steel and contribute a relatively good mechanical strength to the assembly. However, to enable the passage of electric current, it is necessary to attach elements of copper. For this purpose, there is added to the projecting portion of the shaft, a part provided with a sleeve and with a flange or "tulip" of copper against the steel flange of the roller. This tulip is connected electrically to the face of the roller and the current is led on to said tulips through two collectors arranged close to the ends of the shaft.
This roller construction presents however numerous drawbacks and in particular:
IT NECESSITATES MULTIPLE FASTENINGS, HENCE EXPENSIVE MANUFACTURE; AND WITH TIME, THESE FASTENINGS DEVELOP PLAY;
THE STEEL FLANGES ARE MADE FAST TO THE CENTRAL SHAFT BY A WELD AND THIS WELD CONSTITUTES A SOURCE OF SERIOUS OCCURENCES ON THE LATTER, OFTEN LEADING TO RUPTURE;
THE JUXTAPOSITION OF PARTS AGAINST ONE ANOTHER CAN LEAVE A PASSAGE FOR ACID OR OTHER INFILTRATIONS RESULTING, ON THE SHAFT, AT THE MOST SENSITIVE AND MECHANICALLY WEAKEST POINT, IN CORROSION JEOPARDISING ALSO THE PERFORMANCE OF THE SHAFT; HERE AGAIN, THESE PHENOMENA CAN RESULT IN THE RUPTURE OF THE LATTER;
THE ARRANGEMENT OF THE INLET AND OUTLET FOR COOLING WATER MAKES COMPLETE DRAINAGE OF THE ROLLER VERY DIFFICULT.
The above drawbacks arise directly from this construction which has the major disadvantage of not preserving the most sensitive section of the shaft situated perpendicular to the flanges.